Process of smelting lead ores.



N0. 816,764. PATENTED APR. 3, 1906. W. VALENTINE & A. G. BBTTS.

PROCESS OF SMELTING LEAD ORES. I

APPLICATION FILED JUNE 15, 1904.

2 SHEETS-SHEET 1.

W jw mdmj wm No. 816,764. PATBNTED APR. 3, 1906.- W. VALENTINE & A. G. BETTS.

PROCESS OF SMELTING LEAD ORES.

APPLIOATION FILED JUNE 15, 1904.

2 SHEETS-SHEET a.

Fly. 2 26 Mg W UNITED STATES PATENT OFFICE.

WILLIAM VALENTINE AND Anson GARDNER BETTS, or TROY, NEW YORK.

PROGESS OF SMELTING LEAD CRES- Specification of Letters Patent.

Patented April 3,1906.

Application filed June 1.6, 1904. Burial No. 212,745.

To all whom it may concern:

Be it known that we, WILLIAM VALENTINE a subject of the King of Great Britain, an ANsoN GARDNER BETTS, a citizen of the United States, and residents of Tro New York, have invented certain new an useful Improvements in Processes of Smelting Lead Ores, of which the following is a specification, accompanied by drawings.

Figure 1 of the drawings is a plan of the apparatus'in which our processes are carried out, and Fig. 2 shows in vertical section the details of our electrolyzing-furnace.

The principal objects of our invention are to recover lead and sulfur from ores containing galena without appreciable loss of lead. Other objects will appear in connection with the following description of our process.

Our invention consists in freeing the metallic sulfids of the ore from the earthy gangue by fusion. and in reducing lead from the lead sulfid by bringing the sulfid'into contact with a cathode In a bath of afused Pb Fe FeO Zn CaO Insol (SiO,.Al,O,) S

i Per cent. Per cent. Per crnt. Per cent. Per cent. Per cent. Matte 67.78 10.6 1.0 trace trace 19,83 Slag 11.77 20.37 1.6 18.5 80.5 2.1

Matte 75.44 6.6 1.0 trace trace 14.28 Slag 12.84 27.22 1.2 18.60 82. 1.94

The elimination of gangue by a preliminary fusion is a desirable step in the preparation of lead ore for treatment by other processes for instance, electrolysis of lead sulfid dissolved in fused lead chloridand for the reduction of lead from the sulfid by smelting with carbon and sodium carbonate with or without the use of iron oxid. (See, respectively, applications for Letters Patent of Anson G. Betts, Serial No. 208,947, filed May 20, 1904, and No. 208,946, filed May 20,1904.)

We prefer to further treat the fused matte directly, Without-allowing it to cool to the solidifying point.

Our electrolyzing apparatus consists of a furnace on the bottom of which is a suitable cathode, usually molten lead; but other electrodes may be usedfor instance, carbon. Above the cathode We keep a layer of matte containing lead sulfid, usually though not necessarily liquid, and above the matte a fused electrol te in whichlead sulfid is substantially other cathion appearing at the cathode reacts with lead sulfid, giving metallic lead and sodium sulfid or other sulfid. The sodium sulfid formed when the electrolyte contains sodium chlorid partly dissolves in the matte and partly in the electrolyte. It thus happens that in-case the bath on the start contains only sodium chlorid sodium sulfid accumulates in the electrolyte, so that sulfur chlorid soon appears at the anode, and eventually pure sulfur is given off.- The matte from which the contained lead has been largely reduced is taken from the furnace, preferably b tapping, and fresh matte high in lead adde We prefer to make the charging and tapping processes nearly continuous, so that the matte in the furnace does not vary greatly in composition and may have about the following composition: FeS, 47.9 per cent., ZnS, 7.8 per cent., PbS, 22.4 per cent; Na S, 8.4 per cent; NaCl, 8.5 per cent., Gas, 4.3 per cent.

If the matte charged contains FeS 15.7 per cent., ZnS 2.5 per cent., and PbS eighty per cent., the percentage of the lead extracted in the electrolyzing-furnace is about ninetyone per cent.

The matte ta ped from the furnace can be easily leache as it rapidly disintegrates when placed in water. The salt and sodium sulfid which dissolve may be recovered by evaporation and added to the electrol to in the electrolyzing-furnztce. It is desira le to add an amount of sodium sulfid to the electrolyte from time to time sufficient to replace that taken out with the matte tapped, as

ones in a otherwise chlorin will come ofl with the sulfur. After extracting salt and sodium sulfid from the tapped matte the residue is so porous that it takes fire on drying and may be ermitted to roast before further treatment. The roasted product may be added to the ore-melting process. In melting the ore we refer to use a reverberatory furnace and 'to izeep the atmosphere in the furnace reducing to prevent loss of lead by volatilization. We can add natural galena direct to the electrolyzing-furnace, particularly when nearly free from earthy gangue.

Our recess is particularly applicable to -'extract1ng lead from other kinds of matte for exam 1e, that produced in smelting lead last-furnace.

Mattes are not true electrolytes, as they permit the passa e of an electric current without electrolysis, so that the are not well suited for direct electrolysis. his difficulty is obviated in our process, as is apparent from the foregoing description.

Having re erence to the accom anying drawings, in Fig. 1 we have shown in orizontal section a reverberatory furnace of the usual construction, in whlch l is the fireplace; 2 firing-doors; 3, working doors; 4, the stacic; 5, the tap-hole for matte, and 6 the .Lslag-tap. The slag is tapped into the pot 7 and removed and the matte into pots 8, with a tap-hole 9 near the bottom. The matte is wheeled on themain floor 10 to a position above the electrolyzing-furnaces 11 and the spouts 12 and tap ed from the pot 8, while still liquid, into t ie furnaces 11. The metallic lead and matte largely freed from lead are tapped at a lower level into a 0t 13. 14 represents bus-bars connecting t e furnaces 11 in electrical series with a direct-current dynamo.

In Fig. 2 we have shown in vertical section the details of our electrolyzing-furnace. The furnace is constructed of refractory material 15, with an iron pan 16 built in to prevent escape of lead. The iron pan is electrically connected to the bath of lead 17 in the furnace by lead in a space 18 left in the refractory material. A layer of matte 19 floats on the lead, and above this is a layer of fused salt 31. It is not necessary, though it is usual, for the matte to be melted, as the process succeeds with solid pieces of matte. The furnace has an iron cover 20, lined with fire-brick 21, with two 0 enings left,.one, 22, for the introduction 0 matte when the cover 23 is removed and the other allowing the passage of a carbon anode 24.

At the end of the carbon anode is connected 9. copper terminal 25, to which is connected the positive conductor 26 of ad name. A hole 27 ,is left throu h the side 0 the furnace for the escape of su fur, which may be condensed or burned. A tap-hole 28, closed by a plug of fire-clay 29, allows for ta ping the furnace and removing matte an( lead. An iron block 30 in contact with the pan 16 extends to the outside'of the furnace and is connected to the negative pole of the source of the electric current.

- It is understood that when the material containin lead sulfid is brought into contact with a cat ode in a fused electrolyte the material being a conductor of the first class may be considered to itself become the cathode.

What we claim as new, and desire to secure by Letters Patent, is

1. The process of recovering lead from lead-sulfid ores which consists 1n fusing the ore and accompanying gangue into a matte and a slag, and electrolytically separating lead from the matte by bringing the matte into contact with a cathode in a fused electrol te in which lead sulfid is substantially inso uble.

2. The process of recovering lead from lead-sulfid ores which consists in fusing the ore and accompanying gangue into a matte and a slag, and electrol tically separating lead from the matte by bringing the matte into contact with a cathode in a fused electrolyte containin a dissolved sulfid, and in which lead sulfid is substantially insoluble.

3. The process of recoverin r lead from lead-sulfid ores which consists in fusing the ore and accompanying gangue-into a matte and a slag, and electrol tlcally separating lead from the matte b )ringing the matte into contact with a cat 10(18 in an electrolyte of fused sodium chlorid, containing sodium sulfid.

4. In the electrol tic process of reducing lead from lead sulfid by reduction at a cathode in a fused electrolyte which does not dissolve lead sulfid to a substantial degree, the step of adding a sulfid soluble in the electrolyte.

5. In the electrol tic process of reducing lead from lead sulfid by reduction at a cathode in an electrolyte of fused sodium chlorid,

.the step of adding sodium sulfid to the electrolyte.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

WILLIAM VALENTINE. ANSON GARDNER BETTS.

Witnesses:

ETHEL K. BETTS, EDWARD F. KENI. 

